152 results about "Network allocation vector" patented technology

A technique for multiple receiver aggregation that allows for multiple immediate responses of acknowledgements or block acknowledgements. The technique uses a spoofed network allocation vector (NAV) implemented within an aggregate's PLCP header to protect the aggregate and all of the immediate responses from multiple receivers. The immediate responses are scheduled, the information indicating the scheduled offset time and granted transmission duration for response of each receiver being included in the physical sublayer data unit (PSDU) headers within the aggregate.

Embodiments of the present invention include a wireless access method based on a NAVT (Network allocation vector table), which is applied to a distributed wireless mobile communication system comprising a plurality of nodes, the NAVT comprises a packet type field and a duration field and is stored in the respective nodes of the communication system, comprising: on a transmitting side, determining whether only a RTS (request to send) item is contained in the NAVT when a packet arrives; sensing channel to judge whether the channel is busy after determining that only the RTS item is contained in the NAVT; sending a RTS packet based on the RTS item to the receiving side after determining that the channel is busy; and on a receiving side, determining whether the NAVT is empty or not when the RTS packet is received; sending a CTS (clear to send) packet back to the transmitting side after determining that the NAVT is empty.

A medium access control (MAC) protocol is provided for avoiding collisions from stations (STAs) comprising two or more IEEE 802.11 basic service sets (BSSs) collocated and operating in the same channel during contention free periods (CFPs). The MAC protocol includes hardware / software for utilizing ready-to-send (RTS) / clear-to-send(CTS) exchange during CFPs to avoid potential collision from STAs in overlapping BSSs and hardware / software for providing overlapping network allocation vectors (ONAV) in addition to a network allocation vector (NAV), the ONAV included to facilitate the effectiveness of the RTS / CTS during CFPs.

A mobile ad-hoc network (MANET) may include a plurality of nodes for transmitting data therebetween using a media access layer (MAC), where each of the nodes has a respective MAC address associated therewith. The MANET may also include a policing node for detecting intrusions into the MANET by monitoring transmissions among the plurality of nodes to detect frame check sequence (FCS) errors from a MAC address, and generating an intrusion alert based upon detecting a number of FCS errors for the MAC address exceeding a threshold. The policing node may also detect intrusions based upon one or more of failed MAC address authentications, illegal network allocation vector (NAV) values, and unexpected contention or contention-free operation.

An 802.11 source station transmits a message, such as a CF-End message, to reset a network allocation vector at a time other than that required for indicating the end of the contention free period. That is, the source station uses the CF-End message to spoof stations within range of the message into resetting the stations' network allocation vectors as if the contention free period were active. Thus, the spoofing source station is allowed to release the medium for general use after the medium has been reserved for a specific use, for a greater time than necessary. Accordingly, spoofed stations may, for example, 1) delay transmission until a more critical transmission has completed, 2) allow unknown or foreign protocol to have preferential use of the medium, 3) prevent interference from hidden stations, and 4) allow sharing of the medium by overlapping basic service sets. After the specific use, if the medium is still reserved, the medium may be released for general use.

An access method for periodic contention-free sessions (PCFS) reduces interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations and an access point (AP) station. The access method for periodic contention-free sessions (PCFS) includes a fixed cycle time that reduces conflicts with PCFS from other cells. The PCFS from several cells are repeated in cycles of cycle period (CP), which is the contention-free period (CFP) of an access point times a factor that is a function of the number of overlapping cells. Periodic contention-free sessions (PCFSs) are generated, one from each overlapping cell. PCFS transmission attempts occur at the fixed specified time spacing following the start of the previous cycle. Each active AP sets a timer at CP and a PCFS is initiated when the timer expires. The timer is then reset to CP and this starts a new cycle. Contention transmissions are attempted by stations based on their assigned priority. If a channel is busy at the designated start time for transmitting a PCFS, the PCFS is shortened by the time lost. Interleaving PCFSs and CFSs reduces conflicts with CFSs from other cells. To lessen the contention between APs of different cells, each station's Network Allocation Vector (NAV) and Inter-BSS Network Allocation Vector (IBNAV) is updated by an increased value of the next CFS length, the increment being the inter-BSS contention period (IBCP). APs will attempt to access the channel during the IBCP only for transmitting a PCFS, while they will wait for the NAV and IBNAV expirations before attempting to transmit a CFS. Interleaving PCFSs and CFSs also enables maintaining quality of service (QoS).

Embodiments of the present invention include a wireless access method based on a NAVT (Network allocation vector table), which is applied to a distributed wireless mobile communication system comprising a plurality of nodes, the NAVT comprises a packet type field and a duration field and is stored in the respective nodes of the communication system, comprising: on a transmitting side, determining whether only a RTS (request to send) item is contained in the NAVT when a packet arrives; sensing channel to judge whether the channel is busy after determining that only the RTS item is contained in the NAVT; sending a RTS packet based on the RTS item to the receiving side after determining that the channel is busy; and on a receiving side, determining whether the NAVT is empty or not when the RTS packet is received; sending a CTS (clear to send) packet back to the transmitting side after determining that the NAVT is empty.

The present invention is related to a medium access control (MAC) protocol for avoiding collisions among ESTAs when two or more overlapping basic service sets (OBSSs) co-exist and operate in the same channel. To achieve this, each mobile station operating under HCF maintains a first counter known as Network Allocation Vector (NAV) and a second counter known as Overlapping Network Allocation Vector (ONAV), which is updated within a mobile station by frames coming from OBSSs, during the Contention Free Period (CFP) or during a Contention Free Burst (CFB) granted by a polling frame. The mobile station uses the NAV to update only to the medium occupancy in its own BSS to ensure that the mobile station will not interfere with the transmissions in its own QBSS, while the ONAV is used to avoid collisions with the mobile stations from the OBSS.

An 802.11 source station transmits a signal with the duration field other than that required for the transmission to prevent transmission by other stations during known sequences. Thus, the source station uses the duration field to spoof the actual time the medium will be occupied, to stations within range of the signal. A station within range of the transmitted signal will check the duration field of the transmitted signal, and update the station's network allocation vector. Thus, the station will not transmit because the station's network allocation vector indicates that the medium is in use, even though the station maybe unable to hear the carrier. Accordingly, spoofed stations may, for example, 1) delay transmission until a more critical transmission has completed, 2) allow unknown or foreign protocol to have preferential use of the medium, 3) prevent interference from hidden stations, and 4) allow sharing of the medium by overlapping basic service sets.

A method and apparatus for preventing a plurality of stations in a wireless local area network (WLAN) where a plurality of high throughput (HT) stations and a plurality of 802.11 legacy stations coexist from colliding are provided. The method includes generating a data frame having an HT format by inserting information indicating that a medium will be unavailable until the reception of an acknowledgement (ACK) frame is concluded into a physical layer (PHY) header having a format that can be interpreted by both the HT stations and the legacy stations; transmitting the data frame; and transmitting a reset frame which resets network allocation vectors (NAVs) of a plurality of stations which have heard the data frame, and has a format that can be interpreted by both the HT stations and the legacy stations. The apparatus includes a data frame generation unit; a reset frame generation unit; and a transmission unit.

Disclosed is a wireless station having a receiver and a network allocation vector associated with each of a plurality of directional antennas. The receivers concurrently listen for frames from remote stations. When any receiver detects a frame from a remote station, the receiver activates its associated NAV. The station has one or more transmitters that can transmit using the antennas. While transmitting a signal using an antenna, the receivers associated with any non-transmitting antennas continue to listen for signals from remote stations. The station cancels any signals from the transmitting antenna received by the non-transmitting antennas. To perform the cancellation, the station performs a self-calibration procedure. The station can self-calibrate by either silencing neighboring stations or by inserting null tones into a transmitted calibration signal.

A method and apparatus are described including multicasting a medium reservation message and receiving a response to the medium reservation message. Also described are a method and apparatus including receiving a medium reservation message, determining if a medium is idle and transmitting a response to the medium reservation message responsive to the determination. Further described are a method and apparatus including receiving a medium reservation message, determining if a received network allocation vector in the medium reservation message has a value greater than a current network allocation vector, determining if transmission over a medium during a time interval is detected and resetting the current network allocation vector responsive to the determination of transmission. Yet further described are a method and apparatus including receiving a response to a medium reservation message, determining if a network allocation vector in the response is greater than a current network allocation vector and updating the current network allocation vector responsive to the determination.

The invention relates to the technical field of wireless communication and discloses a building method for a layer-spanning dynamic source routing protocol based on load balance. With a single-path routing mode adopted and based on the dynamic source routing protocol, the method comprises the following steps: based on IEEE802.11 MAC layer technology, a cycle T is determined, network distribution vectors in a request frame and an allowing frame sent by a neighbor node S are intercepted within the cycle T, and the idle time of the node is calculated to obtain the residual available bandwidth of the node; the residual available bandwidth, the load, the hop count and the data quantity in a buffer queue of the node S are transferred to the network layer to form routing metrics, and a path parameter with the biggest metric is selected; a plurality of gateways used for shifting flows are built for shunting the flows to separate gateway. The building method for the layer-spanning dynamic source routing protocol based on the load balance can maintain the load balance of the whole network, reduce the routing query flooding range, reduce the times of routing discovery and improve the throughput of WMN.

An 802.11 source station transmits a signal with the duration field other than that required for the transmission to prevent transmission by other stations during known sequences. Thus, the source station uses the duration field to spoof the actual time the medium will be occupied, to stations within range of the signal. A station within range of the transmitted signal will check the duration field of the transmitted signal, and update the station's network allocation vector. Thus, the station will not transmit because the station's network allocation vector indicates that the medium is in use, even though the station maybe unable to hear the carrier. Accordingly, spoofed stations may, for example, 1) delay transmission until a more critical transmission has completed, 2) allow unknown or foreign protocol to have preferential use of the medium, 3) prevent interference from hidden stations, and 4) allow sharing of the medium by overlapping basic service sets.

A system and method for improved vertical handoff between different types of wireless network. Network allocation vector occupation and packet collision probability are used as quality of service measures, enabling vertical handoffs to be delayed until actually beneficial to quality of service. Improved wireless network cell boundary detection in vertical handoff scenarios is achieved with a Fourier-based technique in conjunction with an adaptively determined minimum operating signal strength threshold. Improved wireless network cell boundary detection enables vertical handoffs from high quality of service networks to be delayed as long as possible. Together, practical wireless network quality of service measures and improved detection of wireless network cell boundaries in vertical handoff scenarios reduce the rate of unnecessary vertical handoff resulting in higher overall quality of service experienced by a mobile computing device roaming between wireless network types.

The present invention relates to a wireless LAN (Local Area Network) communication system. Upon a timer unit 108 clocking a predetermined time T after an access point 100 has transmitted a beacon signal 200, a transmission frame control unit 105 generates a CTS frame 301, and transmits an error frame 401 via a transmission frame generation unit 106, a wireless transmission unit 107 and an antenna 109. Accordingly, upon receiving the CTS frame 301, a communication terminal 20 ceases transmitting data for a NAV (Network Allocation Vector, transmission prohibition interval) period in accordance with IEEE 802.11 standard.

Certain aspects of the present disclosure provide techniques and apparatus for signaling the bandwidth to be used for wireless communications using an RTS / CTS (Request to Send / Clear to Send) frame exchange, providing for bandwidths of at least 20 MHz, 40 MHz, 80 MHz, 160 MHz, or higher. This exchange of bandwidth information may be performed implicitly-by determining the channels in which the RTS / CTS frames are actually sent-or explicitly. In addition to this bandwidth information exchange, aspects of the present disclosure may also allow for Network Allocation Vector (NAV) protection in multiple channels. In this manner, the wireless medium may be reserved, and the transmission may be protected from hidden nodes.

Embodiments of the present invention include a method and apparatus for reducing control signaling overhead in a hybrid wireless network. The method comprises receiving a wireless frame in the hybrid wireless network at a first terminal, and determining whether the received wireless frame is a control frame for a wireless channel reservation; if the received wireless frame is a control frame for the wireless channel reservation, reading by the first terminal a value of Duration field in control frame, and updating a timer for a channel reservation period in the first terminal with the value of Duration field, instead of updating network allocation vector of the first terminal; determining whether the remaining time of the timer for the channel reservation period is longer than the time required for transmitting the data frame or not before transmitting a data frame by the first terminal; and transmitting the data frame directly by the first terminal without transmission of a control frame for the wireless channel reservation if the remaining time is longer than the time required for transmitting the data frame.

The invention discloses a multi-frame transmission method. The method comprises the following steps that: based on amount and / or length of data to be sent to the current receiving station in the current access queue, a sending station determines the time for occupying a channel to perform frame exchange with the current receiving station; the sending station generates channel reservation time information according to the determined time for occupying the channel to perform frame exchange with the current receiving station; and the sending base station performs frame exchange with the current receiving station according to the generated channel reservation time information. The invention further discloses a multi-frame transmission system. With the method and the system, the channel reservation time of the stations in an OBSS (Object Based Storage System) is reduced, thus, an auditing station can set shorter NAV (Network Allocation Vector) settings, the system throughput of the OBSS is improved, and the high efficiency of each station in the OBSS under the condition of large-bandwidth is ensured.

An access method for periodic contention-free sessions (PCFS) reduces interference between overlapping first and second wireless LAN cells contending for the same medium. Each cell includes a respective plurality of member stations and an access point (AP) station. The access method for periodic contention-free sessions (PCFS) includes a fixed cycle time that reduces conflicts with PCFS from other cells. The PCFS from several cells are repeated in cycles of cycle period (CP), which is the contention-free period (CFP) of an access point times a factor that is a function of the number of overlapping cells. Periodic contention-free sessions (PCFSs) are generated, one from each overlapping cell. PCFS transmission attempts occur at the fixed specified time spacing following the start of the previous cycle. Each active AP sets a timer at CP and a PCFS is initiated when the timer expires. The timer is then reset to CP and this starts a new cycle. Contention transmissions are attempted by stations based on their assigned priority. If a channel is busy at the designated start time for transmitting a PCFS, the PCFS is shortened by the time lost. Interleaving PCFSs and CFSs reduces conflicts with CFSs from other cells. To lessen the contention between APs of different cells, each station's Network Allocation Vector (NAV) and Inter-BSS Network Allocation Vector (IBNAV) is updated by an increased value of the next CFS length, the increment being the inter-BSS contention period (IBCP). APs will attempt to access the channel during the IBCP only for transmitting a PCFS, while they will wait for the NAV and IBNAV expirations before attempting to transmit a CFS. Interleaving PCFSs and CFSs also enables maintaining quality of service (QoS).

A method and apparatus of accessing a channel in a wireless local area network is provided. A destination station receives a request to send (RTS) frame to allocate a network allocation vector from a source station over a first bandwidth and transmits a clear to send (CTS) frame over a second bandwidth to the source station in response to the RTS frame. The second bandwidth is dynamically determined when a first parameter has a predetermined value.

The invention relates to a distributed channel allocating method in a multi-channel multi-radio wireless Mesh network, which comprises the steps of: initiating a route request by a node needing route discovery, after a target node receives a request message, figuring out a channel free degree and a surplus available bandwidth through a network allocation vector (for short NAV) when replying along a reverse route, solving weighted average expected transmission time (WA ETT), selecting a channel with the minimum WA ETT as a channel for allocating to a link, after allocating the channel for each jump in each path, respectively figuring out a value of a route metric EWCETT (Evoluted Weighted Accumulation Expected Transmission Time) of each path, and selecting the path with the minimum EWCETT value as an optimal route for transmitting and maintaining. According to the invention, channel allocation and route selection are fused together, the time of channel allocation and route selection is effectively reduced, and network throughput, end-to-end time delay and network overhead of the multi-channel multi-radio wireless Mesh network can be effectively improved.

The invention discloses a space division interference avoiding method for a wireless local area network OBSS (object-based storage system) site. The method comprises the following steps: step 1, a site at the OBSS is enabled to carry beam vector information used by the site through modifying the structure of an RTS (ready to send) frame and a CTS (clear to send) frame, and an MU-MIMO (multi-user multi-input multi-output) sending mode is realized; and step 2, interference AP (access point) in the MU-MIMO sending mode considers the zero-forcing beam direction as an extra constraint condition in the protection time interval of network allocation vector. The space division interference avoiding method for the wireless local area network OBSS site can effectively satisfy the service quality requirement of the site at the OBSS under scarce spectrum resource.

The embodiment of the invention provides methods and devices for sending and receiving data, and a network system. The method for sending the data comprises the following steps of: broadcasting a request to send announcement (RTSA) which carries a user address list; sending a request to send (RTS), and receiving a clear to send (CTS) returned by an opposite end in response to the RTS; and sending data to the opposite end, wherein the user address list is used for indicating whether a user receiving the RTSA is provided with a network allocation vector (NAV) after receiving the RTS or the CTS. According to the embodiments of the invention, the RTSA is added so as to be used as supplementation and expansion of an RTS / CTS mechanism; an STA user receiving the RTSA selects whether to be provided with the NAV according to the indication of the user address list in the RTSA after receiving the RTS / CTS, and can timely reply the data sent by a data sending end; and therefore, the problems of mutual confliction, difficult realization and the like in the prior art are solved, and an effective protection mechanism is supplied to data transmission.

The invention discloses nodes and NAV (network allocation vector) control method, device and system therefor. The method includes: judging that a preset first field of a monitored MAC (media access control) frame carries a first identifier, upgrading a local NAV value into a preset first value smaller than the local current NAV value; and after a TXOP (transmit opportunity) responder receives a last MAC frame transmitted by a TXOP holder, transmitting the MAC frame with the preset first field carrying the first identifier. The method, device, system and nodes allow hidden sites to timely compete for channel access, so that the problem of regional discrimination is solved for the sites.

A power management method. The power management method for a wireless network having a plurality of stations (STAs) comprises receiving a data frame, detecting a destination STA in accordance with the data frame, and entering a low power state if not the destination STA for a first power-save (PS) duration determined according to a network allocation vector (NAV) of each STA not the destination STA, updated with a duration information of the received data frame duration determined according to a network allocation vector (NAV) of the data frame.

A method, apparatus and computer readable medium for an RTS / CTS system that utilizes a plurality of channels for data transfer, includes sending, by a first device, an RTS frame over the plurality of channels; receiving, by a second device, the RTS frame and outputting a CTS frame to the first device based on receipt of the RTS frame, the CTS frame being output over at least one of the plurality of channels; setting, by each device within a network that receives the RTS frame, a network allocation vector (NAV) to a time duration that is based in part on information included in the RTS frame; and transmitting, by the first device, data to the second device within the time duration set by the NAV using the at least one of the plurality of channels.

Techniques for reducing delay in scheduling traffic transmission in an overlapping basic service set (OBSS) environment by modifying backoff mechanisms are disclosed. In some examples, a device (e.g., station (STA) or access point (AP)) may decode at least a portion of a preamble of a received packet to determine whether the packet is sent by a member of an OBSS (e.g., STA or AP from a different BSS). Backoff operations are typically deferred as a result of the decoding. Aspects of the present disclosure provide a method, apparatus, and system to reduce delay in scheduling traffic transmissions by resuming the backoff operations prior to expiration of the period reserved for an OBSS packet by the network allocation vector (NAV). In other words, the device may not honor the NAV of the OBSS packet, and instead perform spatial reuse by transmitting another packet (or signal) on the same frequency channel during the NAV of the OBSS packet.

The invention provides a method and apparatus for network allocation vector (NAV) resetting. The method comprises the following steps that: a radio station receives a radio frame carrying time length indication information; the radio station updates a local NAV according to the time length indication information; and the radio station determines whether a frame switch sequence initiated by the radio frame is failed to be sent; if so, the NAV is reset. According to the invention, a problem that all stations can not compete for channels fairly when a frame switch sequence is failed can be solved, thereby enabling all the radio stations to compete for channels quickly and further improving a channel utilization rate.